Belsomra (Suvorexant) Side Effects
The most common side effect of Belsomra is next-day drowsiness, occurring in approximately 7% of patients (compared to 3% with placebo), but serious neuropsychiatric effects including complex sleep behaviors, sleep paralysis, worsening depression with suicidal thoughts, and temporary leg weakness (cataplexy) can also occur. 1, 2
Most Common Side Effects
- Somnolence (daytime drowsiness) is the most frequently reported adverse effect, affecting approximately 7% of patients versus 3% with placebo 1, 3
- This drowsiness is dose-dependent, with higher frequencies at doses exceeding FDA-recommended levels 1
- Next-day impairment can affect driving ability and activities requiring full mental alertness, particularly at the 20 mg dose 2
- Headache is commonly reported across clinical trials 4
- Abnormal dreams have been documented as an additional side effect 2, 5
Serious Neuropsychiatric Side Effects
- Complex sleep behaviors can occur, including sleep-walking, sleep-driving, preparing and eating food, making phone calls, having sex, or other activities while not fully awake that patients may not remember the next morning 2
- Worsening depression and suicidal thoughts have been reported during treatment with Belsomra and require immediate medical attention 2
- Sleep paralysis (temporary inability to move or talk) can occur for up to several minutes while going to sleep or waking up 2
- Temporary leg weakness (cataplexy-like symptoms) can happen during the day or at night 2
- Amnesia, anxiety, and hallucinations are listed as potential neuropsychiatric symptoms 1
Additional Reported Side Effects
- Dizziness has been documented in clinical trials 4
- Diarrhea occurs in some patients 4
- Cough and upper respiratory tract infection have been reported 4
- Profuse sweating (hyperhidrosis) has been reported, though not well-documented in clinical trials, possibly related to orexin system effects on autonomic nervous system regulation 1
Dose-Dependent Considerations
- Higher doses (30-40 mg) showed better efficacy but were rejected by the FDA specifically due to dose-dependent increases in daytime somnolence (up to 8.4% versus 3.1% with placebo at 15/20 mg doses) 1
- Lower doses (5-10 mg) offer improved safety profiles while maintaining efficacy for sleep maintenance 1, 3
- The 20 mg dose carries the highest risk of next-day impairment and driving impairment 2
Important Safety Warnings and Contraindications
- Alcohol interaction: Do not drink alcohol while taking Belsomra, as it increases the risk of serious side effects 2
- Contraindicated in narcolepsy: Patients who fall asleep often at unexpected times should not take Belsomra 2, 5
- Drug interactions: Monitor for interactions with SSRIs and other serotonergic agents, which may have additive effects 1
- Strong CYP3A inhibitors: Suvorexant should be avoided in combination with strong CYP3A inhibitors 5
- Pregnancy and breastfeeding: It is not known if Belsomra can harm an unborn baby or passes into breast milk 2
Special Population Considerations
- No dose adjustment needed for advanced age, according to the American Geriatrics Society 3, 5
- Higher drug levels occur in women and obese people; dosing should be conservative in obese women 5
- Caution in respiratory disease: Precautions exist for patients with lung problems or breathing problems 2, 6
Clinical Context and Comparative Safety
- Suvorexant does not cause the severe adverse effects associated with zolpidem, such as amnesia, vertigo, confusion, and diplopia 1
- The frequency and severity of adverse effects are generally lower than with traditional hypnotics 1
- No strong signals for rebound or withdrawal were seen after 1-12 months of treatment 7
- Residual morning sedation can occur, though absolute rates are generally low at approved doses 1